Foreword DTMF dual tone multifrequency The signal is a commonly used signalling in the telephone network, no matter on home telephones, cellular telephones or SPC exchanges, adopt DTMF signal transmission receiving numbers more. DTMF technology can also be used for occasions such as power line carrier communication,etc.. It is obvious, DTMF has extensive application to dial and decode in communication system and others. Usually the detection of DTMF signal is realized by special purpose chip or DSP, but its great of cost. This text has introduced a kind of low-cost DTMF dialing demoder based on MSP430F133 and realized the scheme. MSP430F133 one 16 the intersection of RISC and the intersection of structure and MCU of TI, most short instruction cycle 150ns, contain 8KB Flash ROM, 256B RAM and built-in 12 ADC.

DTMF signal DTMF to amount to 16 character 0~9, A on the dial plate D and * / E, # / F in signal, come on a encoder mode that show with 8 frequency of audiorange. 8 frequency divide into high-frequency cluster and the intersection of low frequency and the intersection of cluster and two set, respectively as list frequently and horizontal frequency. Each Read more